1. Field of Invention
The present invention relates to a valve for a gas can.
2. Related Prior Art
Referring to FIGS. 8 and 9, there is shown a conventional valve for a gas can. The valve includes a shell 10′ and a core 20′. The shell 10′ defines a first space 11′ and a second space 16′ in communication with the first space 11′. A spring 12′ is positioned in the first space 11′. A ring 13′ is positioned in the second space 16′. The ring 13′ includes an annular flange 14′ on an internal side. An annular restraint 15′ is positioned in the second space 16′. The core 20′ defines a space 21′ and an aperture 22′ in communication with the space 21′. The core 20′ includes a closed end and an open end. Formed on an external side of the core 20′ are a first abutment portion 23′ and a second abutment portion 24′.
Referring to FIG. 8, the closed end of the core 20′ is normally located in the first space 11′ of the shell 10′ while the abutment portions 23′ and 24′ of the core 20′ are located in the ring 13′. The first abutment portion 23′ abuts the annular restraint 15′. The aperture 22′ is located outside the second space 16′ of the shell 10′. Gas goes into a space (“effective space”) between the ring 13′ and the abutment portions 23′ and 24′ of the core 20′ from the first space 11′ of the shell 10′, past the annular flange 14′. The gas does not leave the effective space.
Referring to FIG. 9, to release the gas, the open end of the core 20′ is pushed. The second abutment portion 24′ of the core 20′ contacts the flange 14′ so that the gas does not go into the effective space from the first space 11′ of the shell 10′. On the other hand, the aperture 22′ is moved into the effective space so as to allow the gas to go into the space 21′ of the core 20′ from the effective space through the aperture 22′ of the core 20′. Every time the open end of the core 20′ is pushed, a predetermined amount of gas leaves the effective space.
There are problems with this conventional valve. The ring 13′ including the flange 14′ is made of plastic, and it is difficult to precisely control the dimensions of the ring 13′ including the flange 14′. In the case where the flange 14′ is made too large, it contacts the second abutment portion 24′ of the core 20′ even in the normal position so as to prevent the gas from entering the effective space. Thus, in the releasing position, an inadequate amount of gas leaves the effective space. In the case where the flange 14′ is made too small, it fails to contact the second abutment portion 24′ of the core 20′ even in the releasing position, thus allowing the gas to continue to go into the effective space. Hence, an excessive amount of gas leaves the effective space.
Referring to FIGS. 10 and 11, there is shown another conventional valve for a gas can. This conventional valve includes a shell 10″, a first tube 20″ and a second tube 30″. The shell 10″ defines a space 11″ for receiving the tubes 20″ and 30″ and a spring. The first tube 20″ defines a first tunnel 22″ and a second space 23″ in communication with the first tunnel 22″. The spring is compressed between an internal end of the first tube 20″ and the wall of the space 11″ of the shell 10″. The second tube 30″ includes a closed end and an open end. The second tube 30″ defines a space 31″, an outlet 32″ in communication with the space 31″ and an intake 33″ in communication with the space 31″.
Referring to FIG. 10, the closed end and outlet 32″ of the second tube 30″ are normally located in the second space 23″ of the first tube 20″. Hence, gas does not go into the first tunnel 22″ of the first tube 20″.
Referring to FIG. 11, to release the gas, an external end of the first tube 20″ is pushed. Thus, the outlet 32″ of the second tube 30″ is located in the first tunnel 22″ of the first tube 20″. Hence, the gas goes into the first tunnel 22″ of the first tube 20″ from the space 31″ through the outlet 32″ of the second tube 30″. Accordingly, the gas leaves the space 11″ of the shell 10″.
There are problems with this conventional valve. The dimensions of the first tube 20″ are predetermined. For insertion into the first tube 20″, the second tube 30″ must be thin. However, it is difficult to form a thin tube like the second tube 30. It is also difficult to make small holes like the intake 33″ and the outlet 32″. Moreover, as the outlet 32″ is small and might be jammed by the gas so that the valve might release an inadequate amount of gas every time the first tube 20″ is pushed.
The present invention is intended to obviate or at least alleviate the problems encountered in prior art.